Ans is 10 overlaps
There are 11 overlaps in 12 hour period.
ie from 12 noon to 12 midnight.
List of overlaps times:
(both AM and PM)
01)01:05:27
02)02:10:55
03)03:16:22
04)04:21:49
05)05:27:16
06)06:32:44
07)07:38:11
08)08:43:38
09)09:49:05
10)10:54:33
11)12:00:00(not to be count in this question)
hence ans is 10 times overlap